A 'distal step' relationship between the primary second molars (where the mandibular primary second molar's distal surface is positioned more posteriorly than the maxillary) is predictive of a developing tendency toward which permanent molar relationship?

A distal step terminal plane relationship in the primary dentition is associated with a developing tendency toward a Class II permanent molar relationship, reflecting comparatively less favorable mandibular growth/positioning relative to the maxilla. (A flush terminal plane is more associated with eventual Class I, and a mesial step is associated with a tendency toward Class III.)